DESCRIPTION

numactl runs processes with a specific NUMA scheduling or memory
placement policy. The policy is set for command and inherited by all
of its children. In addition it can set persistent policy for shared
memory segments or files.
Use -- before command if using command options that could be confused
with numactl options.
Policy settings are:
--interleave=nodes,-inodes
Set a memory interleave policy. Memory will be allocated using
round robin on nodes. When memory cannot be allocated on the
current interleave target fall back to other nodes. Multiple
nodes may be specified on --interleave, --membind and
--cpunodebind. You may specify "all", which means all nodes in
the current cpuset. nodes may be specified as N,N,N or N-N or
N,N-N or N-N,N-N and so forth. Relative nodes may be specifed
as +N,N,N or +N-N or +N,N-N and so forth. The + indicates that
the node numbers are relative to the process’ set of allowed
nodes in its current cpuset. A !N-N notation indicates the
inverse of N-N, in other words all nodes except N-N. If used
with + notation, specify !+N-N.
--membind=nodes,-mnodes
Only allocate memory from nodes. Allocation will fail when
there is not enough memory available on these nodes. nodes may
be specified as noted above.
--cpunodebind=nodes,-Nnodes
Only execute command on the CPUs of nodes. Note that nodes may
consist of multiple CPUs. nodes may be specified as noted
above.
--physcpubind=cpus,-Ccpus
Only execute process on cpus. This accepts physical cpu numbers
as shown in the processor fields of /proc/cpuinfo, or relative
cpus as in relative to the current cpuset. You may specify
"all", which means all cpus in the current cpuset. Physical
cpus may be specified as N,N,N or N-N or N,N-N or N-N,N-N and
so forth. Relative cpus may be specifed as +N,N,N or +N-N or
+N,N-N and so forth. The + indicates that the cpu numbers are
relative to the process’ set of allowed cpus in its current
cpuset. A !N-N notation indicates the inverse of N-N, in other
words all cpus except N-N. If used with + notation, specify
!+N-N.
--localalloc,-l
Always allocate on the current node.
--preferred=node
Preferably allocate memory on node, but if memory cannot be
allocated there fall back to other nodes. This option takes
only a single node number. Relative notation may be used.
--show,-s
Show NUMA policy settings of the current process.
--hardware,-H
Show inventory of available nodes on the system.
Numactl can set up policy for a SYSV shared memory segment or a file in
shmfs/hugetlbfs.
This policy is persistent and will be used by all mappings from that
shared memory. The order of options matters here. The specification
must at least include either of --shm,--shmid,--file to specify the
shared memory segment or file and a memory policy like described above
( --interleave,--localalloc,--prefered,--membind ).
--huge
When creating a SYSV shared memory segment use huge pages. Only valid
before --shmid or --shm
--offset
Specify offset into the shared memory segment. Default 0. Valid units
are m (for MB), g (for GB), k (for KB), otherwise it specifies bytes.
--strict
Give an error when a page in the policied area in the shared memory
segment already was faulted in with a conflicting policy. Default is to
silently ignore this.
--shmmodeshmmode
Only valid before --shmid or --shm When creating a shared memory
segment set it to numeric mode shmmode.--lengthlength
Apply policy to length range in the shared memory segment or make the
segment length long Default is to use the remaining length Required
when a shared memory segment is created and specifies the length of the
new segment then. Valid units are m (for MB), g (for GB), k (for KB),
otherwise it specifies bytes.
--shmidid
Create or use an shared memory segment with numeric ID id--shmshmkeyfile
Create or use an shared memory segment, with the ID generated using
ftok(3) from shmkeyfile
--filetmpfsfile
Set policy for a file in tmpfs or hugetlbfs
--touch
Touch pages to enforce policy early. Default is to not touch them, the
policy is applied when an applications maps and accesses a page.
--dump
Dump policy in the specified range.
Valid node specifiers
all All nodes
number Node number
number1{,number2} Node number1 and Node number2
number1-number2 Nodes from number1 to number2
! nodes Invert selection of the following specification.

EXAMPLES

numactl --physcpubind=+0-4,8-12 myapplic arguments Run myapplic on cpus
0-4 and 8-12 of the current cpuset.
numactl --interleave=all bigdatabase arguments Run big database with
its memory interleaved on all CPUs.
numactl --cpubind=0 --membind=0,1 process Run process on node 0 with
memory allocated on node 0 and 1.
numactl --cpubind=0 --membind=0,1 -- process -l Run process as above,
but with an option (-l) that would be confused with a numactl option.
numactl --preferred=1 numactl --show Set preferred node 1 and show the
resulting state.
numactl --interleave=all --shmkeyfile /tmp/shmkey Interleave all of the
sysv shared memory regiion specified by /tmp/shmkey over all nodes.
numactl --offset=1G --length=1G --membind=1 --file /dev/shm/A --touch
Bind the second gigabyte in the tmpfs file /dev/shm/A to node 1.
numactl --localalloc /dev/shm/file Reset the policy for the shared
memory file file to the default localalloc policy.

NOTES

Requires an NUMA policy aware kernel.
Command is not executed using a shell. If you want to use shell
metacharacters in the child use sh -c as wrapper.
Setting policy for a hugetlbfs file does currently not work because it
cannot be extended by truncate.
Shared memory segments larger than numactl’s address space cannot be
completely policied. This could be a problem on 32bit architectures.
Changing it piece by piece may work.
The old --cpubind which accepts node numbers, not cpu numbers, is
deprecated and replaced with the new --cpunodebind and --physcpubind
options.

FILES

/proc/cpuinfo for the listing of active CPUs. See proc(5) for details.
/sys/devices/system/node/node*/numastat for NUMA memory hit statistics.

COPYRIGHT

Copyright 2002,2004 Andi Kleen, SuSE Labs. numactl and the demo
programs are under the GNU General Public License, v.2